Dental pattern



June 9, 1959 B. H. LUND'QUIST ET AL 2,889,598 DENTAL PATTERN Filed Jan.17, 1957 7/ INVENTOR. Q am United DENTAL PATTERN Birger H. Lundquist,Amherst, and Ralph E. Fentner, Cheektowaga, N.Y.

Application January 17, 1957, Serial No. 634,663

3 Claims. (Cl. 22--164) This invention relates to a pattern for andmethod of making dentures and bridgework and more particularly to apattern used in producing in metal the lingual and occlusal portionsonly of the artificial teeth of fixed or removable partial dentures andbridges, the remaining portions of the teeth being completed in plasticin the form of a solid dummy, spacer or pontic.

One of the principal objects of the invention is to obtain precision anduniformity as well as a substantial saving in labor and material inmodeling the lingual and occlusal portions of the teeth of artificialdentures and bridges, this being accomplished by providing a pattern inthe form of a concavo-convex shell made of a plastic which softens underthe application of heat and which conforms to the particular tooth to besubstituted so that theshell can be placed in position in a model of thejaw of the patient, reshaped with a hot spatula or built up by theapplication of wax to conform to the patients bite, jaw and remainingteeth, and then used as a pattern in making a metal casting of this partof the denture.

Another object is to provide such plastic shells in such form that theproper tooth form can readily be selected by the dentist and so that thedentist can readily remove a shell of the desired tooth form from agroup of such shells.

Another object is to provide such shells in multiple units of identicalshells, the shells of each unit conforming to a particular tooth, thisenabling the dentist to restock only those units which requirereplacement.

Another object is to provide a pattern for the lingual and occlusalportions of teeth whichleaves exceptionally smooth and flawless lingualand occlusal surfaces in the metal part of .the "denture.

Another object is to produce a denture having metal lingual and occlusalportions of'the required thickness and strength.

Another object is to produce a pattern which will disintegrate withoutapparent residue in the investment in which the metal is 'cast.

Another object'is to provide an internal anchorage in the concave-convexmetal casting for the plastic with which this casting is filled.

Other objects and advantages of the invention will be apparent from thefollowing description and drawings in which:

Fig. 1 is a plan view of a portion of a patients jaw showing two teethbetween which an artificial tooth is to be supplied in .the form of afixed denture embodying the present invention.

:Fig. .2is a'view similar to Fig. vl showing the two teeth of thepatient ground to anchor inlays for supporting the 'COIIC'aVO-LEOIIVCXshells conforming to the lingual and .occlusal surfacesof thetoothnormally in the space appearingiiniFigs. -l and 2.

Fate-un ied June 9,

Fig. 4 is a fragmentary longitudinal sectional view taken on line 44,Fig. 3.

Fig. 5 is a transverse sectional view taken on line 55, Fig. 3. v

Fig. 6 is a fragmentary plan view of a model made of the portion of thejaw shown in Fig. 2. and showing a concavo-convex shell cut from thestrip, Fig. 3, fitted between model reproduction of the patients teethand anchored by bits of wax, this figure also showing the plasticpattern or shell reformed by the application of a hot tool and by theapplication of a bit of wax to conform it to the bite of the patient.

Fig. 7 is a sectional view of the shell taken on line 7-7, Fig. 6 andshowing a wax sprue forming stem attached thereto.

Fig. 8 is a sectional view through a casting flask of a centrifugalcasting machine and showing the pattern and sprue forming stem, Fig. 7,embedded in an investment.

Fig. 9 is a view similar to Fig. 8 and showing the pattern and sprueforming stem replaced with metal.

Fig. 10 shows the casting and inlays positioned on the model, Fig. 6,and soldered together.

Fig. 11 is a sectional view taken on line l1-lll, Fig. 10 and showingthe denture completed by filling the cavity of the metal casting withplastic to vform the visible side of the artificial tooth of thedenture.

The present invention relates to dentures of the type in which thelingual and occlusal faces of the artificial tooth or teeth, is made ofmetal, such as stainless steel, or gold alloys, to provide the requiredstructural strength and resistance to grinding wear, this metal portionbeing recessed toward the outside. This metal portion is provided withmetal anchorages which removably or permanently anchor to the naturalteeth being bridged. The recess of the metal portion is filled withplastic of a color conforming to the patients teeth and which is builtout to provide the labial or buccal surfaces of the tooth or teeth sothat the artificial tooth or teeth will simulate the adjacent naturalteeth.

As now practiced, following forming the natural teeth to accept theanchorages, such as a metal cap or inlay, and following making animpression and a model of this area of the patients jaw, a pattern ofthe artificial tooth or teeth is carefully sculptured in wax to conformto the bite, jaw and natural teeth of the patient. Following this thelabial or buccal side of the sculptured wax tooth or teeth is hollowedout to provide a cavity. A metal casting, which can also be a one'piececasting, is then made or" the wax pattern and this casting is smoothedand finished and soldered to the anchoring caps or inlays or claspswhich have previously been formed to anchor to the natural teeth. Thecavity or cavities are then filled with plastic to provide a naturalappearance to the labial or buccal sides of the denture and the dentureis ready to be placed.

The sculpturing of the wax pattern is time consuming and requires skill,patience and care to obtain the required structural strength, bite andfit and it is the object of the present invention to greatly reduce thetime, skill, patience and care required for this step by providing apattern which is largely preformed and which requires only incidentalreforming or rebuilding up to achieve the required structural strength,fit and bite of the metal casting.

As illustrative of the present invention, in Fig. l is illustrated aplan view of that portion of a human jaw in which includes a secondbicuspid 11 and a second molar 1-2, the jaw having a space 13 from whichthe first molar was extracted. The invention is illustrated as providingan artificial first molar in the space 13 and which is anchored byinlays to the adjacent natural teeth 11 and 12 although it will beunderstood that the anchorage could be in the form of metal caps, forthe teeth 11 and 12, or

could be removable clasps to these or other teeth. To accept theanchorage inlays, the teeth 11 and 12 are shown as provided with medialgrooves 14 and 15, respectively, and in which the inlays are cemented.From .a wax impression (not shown) a hard setting artificial stone modelis made, this having protuberances 11a and 12:! conforming to thepatients teeth 11 and 12 and having a space 13:: conforming to the space13 of the extracted first molar. In the pattern the protuberances 11aand 12a have grooves 14:: and 15a conforming to the grooves 14- and 15.

As a first step the dentist or laboratory technician can form, frommetal, the inlays 14b and 15!), Fig. 10, these being shaped to fit andanchor in the groove 14a and 15a, respectively, of the model 10a andhence in the grooves 14 and 15 of the patients teeth 11 and 12. Theseinlays 14b and 1552 are later soldered to the metal casting of thelingual and occlusal sides of the artificial first molar to be placed inthe space 13 all as hereinafter described although these inlays may bein the form of a single castmg.

The numeral represents a long narrow strip of a flexible syntheticplastic which softens by the application of heat and which has high tearstrength and maintains its form but can be readily cut to any desiredform. For this purpose, and to provide a casting of the requiredstructural strength the sheet 20 is in the order of from .015 to .030inch thick and is made of a thermo-plastic which softens at betweenabout 150 to about 200 F. A plastic suited for this purpose is highimpact polystyrene.

In the strip 20 shown in Figs. 3-5, it is provided on one side with alongitudinal series of shell-like, concaveconvex protuberances 21 spacedfrom each other and each identical in form. Each is in the form of thelingual face 22 and occlusal face 23 of a first molar normally presentat the space 13 in the human jaw. The concavity of each protuberance orshell 21 is on the buccal and gingival or saddle sides thereof. Thedentist or laboratory technician would have on hand twenty-eightdifferent strips 20, each having protuberances conforming to acorresponding one of the twenty-eight human teeth, the end or wisdomteeth being excepted since these are never reconstructed into dentures.The dentist would use the tooth forms of the particular teeth thedenture is to replace and since in the example illustrated the firstmolar from the space 13 is to be replaced, the protuberances 21 are inthe form of the lingual and occlusal faces only of this particulartooth.

The dentist or laboratory technician then cuts one of the series ofprotrusions 21 at its base from the strip 20 as to produce aconcavo-convex shell having a rim 24 and conforming to the lingual andocclusal faces of the tooth to be replaced. This shell, as a pattern, isthen fitted in the space 13:! of the model 10h with its lingual andocclusal faces properly oriented with reference to the tooth formprotubcrances 11a and 12a of the model. In so fitting, the rim 24 of thepattern or shell 21 will probably have to be cut and shaped to fit thegum and tooth portions of the model and after being so cut the patternor shell 21 can be fixed in position by bits of wax 17 applied in moltenform to bridge and connect the rim or edges 24 of the pattern 21 withthe model 10a.

Following this, with a hot spatula having a temperature above thesoftening point of the pattern or shell 21,

the pattern or shell can be reshaped to conform to the jaw, teeth andbite of the patient. As an example, a flat 25 can be provided in thepattern or shell 21 by applying a hot spatula to this area and exertingthe required pressure to produce this fiat in the pattern. T o conformto the bite of the patient it will generally be found that some areas ofthe occlusal surface of the pattern or shell 21 must be built up orextended outwardly. This can be done by applying a small blob 26 ofmolten wax to the portion of the pattern or shell 21 to be built up andthis blob sculptured with a hot spatula into the required form. Ascompared with the former practice of sculpturing an entire tooth fromwax and then hollowing out its buccal or labial side, it will beappreciated that the pattern or shell 21 is essentially preformed to thedesired shape and also holiowed out so that all that is necessary is toreform it to fit the particular patient. This results in a saving intime, care, patience and skill and greatly facilitates this operation.

To provide a better anchorage for plastic, as hereinafter described. asmall semicircular length 27 of Wire can be inserted into the interiorface of the shell or pattern 21, using either a bit of molten wax or ahot spatula for this purpose. The bend of this piece of wire projectsinto the interior of the shell or pattern.

Following this conventional practice can be followed to complete thedenture. Thus the pattern or shell 21 can be removed from the model 10aand a wax stem or sprue forming member 28 adhered thereto. The flask forcentrifugal casting is shown as including a cylindrical ring 29 and anend head 30 which removably fits one end of the ring 29. This end headis shown as having an indented central portion 31 provided with acentral hole 32. in the indented portion 31 is adhered a mass of Wax 33.The end of the wax sprue forming stem 28 is then adhered to the portionof the mass of wax 33 which is exposed through the hole 32. The end head30 is then applied as the base of the ring 29 with the shell or patterninside the ring. The ring 29 is then filled with a hard setting materialto form an investment 34. The parts are then heated to a hightemperature to melt out the wax 23, 33 and burn out the plastic shell orpattern 21. Accordingly, a cavity is left in the investment 34 whichconforms to the shell or pattern 21, sprue forming stem 28, and theindented portion 31.

The flash or ring 29 is then inverted as shown in Fig. 9 and moltenmetal 40 forced centrifugally into the cavity formed in the investment34 by the indented portion 31. The desk is then put in a centrifugalcasting machine and the metal driven into the cavity.

This metal forms a metal shell 41 exactly conforming to the pattern orplastic shell 21, a sprue 42, and an excess of metal 43 at the outer endof the sprue. The semicircular piece of wire 27 is cast into the shell41. The casting is broken out of the investment and the sprue groundoff. It will particularly be noted that since the pattern 21 wasessentially a smooth surfaced shell, and since any added wax should alsobe sculptured to have a smooth surface, the surface of the casting isalso exceptionally smooth.

The inlays 14b and 15b are then fitted, respectively, in the grooves 14aand 15a of the model 10a. The metal shell 41 is then placed in properposition in the space 13a in the model and is soldered, as indicated at45 and 46, to the inlays 14b and 15b.

Following this the interior of the metal shell 41 is filled with plastic49. This plastic flows around the semicircular piece 27 of wire whichforms an anchor for the plastic when the latter hardens. The plastic isselected to color match the patients teeth 11 and 12 and the verticalface 50 thereof is sculptured to provide a buccal face conforming tothat of a first molar.

The denture is then ready to be fitted into the patients mouth, theinlays 14b and 15b being fitted and cemented, in the grooves 14 and 15.

From the foregoing it will be seen that the present invention provides apartially preformed pattern for dentures of the class described whicheffects a substantial economy in time, and materials, care and patienceof the dentist or laboratory technician and provide a high quality, highprecision denture.

We claim:

1. A pattern used in producing in metal the lingual and occlusalportions of an artificial tooth in a denture, comprising a solid walledshell consisting substantially entirely of a convex lingual and occlusalsurface on the outside and a conforming concave surface on the inside,the shell being open on the buccal and gingival sides thereof and beingcomposed of a thermoplastic resin which softens under heat and having asubstantially uniform wall thickness, measured from said inside to saidoutside surfaces, of from 15 to 30 thousandths of an inch whereby thepattern can be deformed, without diminution of said wall thickness, toconform to the bite of the patient and whereby when reproduced in metalas a casting the corresponding open buccal and gingival sides of themetal casting can be filled with moldable plastic which hardens to formthe buccal and gingival surfaces of said artificial tooth.

2. A pattern as set forth in claim 1 wherein the thermoplastic resin isa high impact polystyrene which softens to a readily deformablecondition at a temperature of from about 150 to 200 F.

3. A pattern as set forth in claim 1 and wherein a multiplicity of saidshells are provided in the form of protuberances from a common sheetfrom which said shells are readily cut.

References Cited in the file of this patent UNITED STATES PATENTS2,136,404 Wheeler Nov. 15, 1938 2,345,305 Thornton Mar. 28, 19442,362,507 Steinbeck et al. Nov. 14, 1944 2,461,416 Erdle et a1. Feb. 8,1949 2,638,632 Glazyer May 19, 1953 2,700,184 Levine Jan. 25, 1955

